1. Field of the Invention
The present invention relates to an hydrated EGR system, method and exhaust treatment apparatus for use in a vehicle having an internal combustion engine, to simultaneously reduce harmful exhaust emissions, improve engine performance and increase fuel economy. More specifically, the present invention relate to a hydrated EGR system, method and exhaust treatment apparatus in which heat from an exhaust pipe heats an aqueous fluid solution in a tank, and a portion of hot exhaust gas is bubbled through the heated aqueous fluid solution to form a hydrated EGR mixture containing water vapor. The hydrated EGR mixture is then fed to an intake portion of the engine, using pressure from the exhaust system, and the hydrated EGR mixture is burned with the air/fuel mixture as part of the combustion charge.
2. Description of the Background Art
In efforts to reduce global-warming gas emissions, energy-efficient internal combustion engines may be advantageously used. Many of the known engines today recycle part of the exhaust gas back into the intake manifold via an exhaust gas recirculation (EGR) system. The introduction of some exhaust gas into the intake charge tends to reduce oxides of nitrogen (NOx) present in exhaust gas emitted from the vehicle's tailpipe.
Another method of reducing NOx emissions in internal combustion engines is to add water into the air/fuel mixture entering the combustion chamber, to reduce the peak flame temperature. Water additive methods known in the art include 1) water-injection, 2) water-fuel emulsion, and 3) water-fumigation.
Examples of patents relating to water injection methods include U.S. Pat. No. 4,519,341, U.S. Pat. No. 4,311,118, and U.S. Pat. No. 4,800,848. Other patents which suggest the use of water or water vapor as a component of the combustion charge include U.S. Pat. Nos. 3,552,364, 3,655,169, 4,306,520, 4,337,731, 5,718,194, 6,817,348, 6,892,531, and 7,051,720.
However, water-addition methods including the EGR process are not widely practiced in engine systems, partly because of concerns about possible engine wear problems caused by the potential break-down of the protective film of lubricating oil by contact with water in critical rubbing metal surfaces, such as the surfaces between piston rings and cylinder walls and valve bearings, etc.
It is therefore, desirable to develop a system for engines that further reduces emissions using a method of injecting heated water vapor into an engine.
Due to increasing fuel costs there is also a need to improve fuel efficiency. Further, there is also an ongoing need to increase engine power.
An improved engine system is therefore needed, which would more effectively reduce unwanted pollutants. In particular, an engine system is needed which is operable to reduce emissions of oxides of nitrogen (Nox), while simultaneously improving fuel efficiency and increasing engine power.